BAGHDAD — In a coordinated display intended to show they remain a viable force, Iraqi insurgents launched at least 40 attacks throughout the country Monday, setting off car bombs, storming a military base, attacking police in their homes, and ambushing checkpoints, Iraqi authorities said.
More than 100 people were killed and more than 300 wounded in the single bloodiest day in Iraq in two years, according to Iraqi officials in the many areas where attacks took place.
The attacks, coming in the early days of Ramadan, the monthlong Muslim religious rite, were predicted Sunday in an audio message attributed to the leader of Al Qaeda in Iraq, Abu Bakr al-Baghdadi, and posted on the group’s website. Baghdadi vowed that a new offensive, which he called Breaking Down Walls, would begin soon.
The offensive was without precedent this year, at least in the sheer number of attacks, spread over so many locations in a third of Iraq’s 18 provinces, from north to south. It was sure to raise concerns about the government’s ability to contain the violence six months after the last US troops left the country.
The death toll was the worst for a single day in Iraq since May 10, 2010, when a string of nationwide attacks killed at least 119 people.
‘‘I think Al Qaeda in Iraq made a big joke of the government and the Iraqi security forces,’’ said Khalid Fadel, a military analyst and former instructor at the Iraqi Military College.
‘‘They were so clear that they were going to launch attacks during Ramadan,’’ Fadel said, “and the government said that they have information of about 30 terrorist groups entering the country, but still the security forces are unable to prevent the attacks.’’
Baghdadi said in the Al Qaeda statement that ‘‘we are returning again to dominate territories we used to dominate, as well as more.’’ He depicted the attacks as part of a battle launched by Sunnis against the country’s Shi’ite leaders and people.
The first attack came at about 5 a.m. Monday when gunmen stormed onto an Iraqi military base near the town of Duluiyah in Salahuddin Province and killed 15 Iraqi soldiers, according to security officials. Four soldiers, including a high-ranking officer, were wounded, and a fifth was taken prisoner by the insurgents, who escaped with him.
Then, in steady succession, mostly from 6 a.m. to 10 a.m., car bombs were set off across the country, from Taji and Husseiniya north of Baghdad, to Sadr City in eastern Baghdad; in Tuz in western Salahuddin Province; Dujail in southern Salahuddin; and Balad and Baqubah, northeast of the capital, according to police, hospital, and Iraqi army officials. Bombs also were set off in the northern cities of Mosul and Kirkuk, and in Diwaniya Province in the south.
The insurgents also attacked the home of a police official in Balad, seriously wounding four family members, and ambushed a checkpoint near Baqubah, killing one policeman.
In all, 40 attacks were reported in at least six provinces.
Eight attacks occurred in Kirkuk Province, mostly targeting police patrols, with eight people killed and 42 wounded.
In Mosul, of the 11 people killed in four attacks there, seven were Iraqi soldiers. Other attacks targeted marketplaces and other places where civilians were sure to become victims.
The offensive started on the third day of Ramadan and apparently took advantage of the widespread practice in Iraq and many other Muslim countries of staying up most of the night, and then sleeping late during the daytime when fasting is required.
The attacks were likely to continue the trend of the first six months since the departure of US troops, when violence has steadily increased, according to United Nations statistics. June was one of the deadliest months so far, with about 200 people, mostly civilian pilgrims, reported killed.
US and Iraqi officials have argued that violence has been declining.
Unusually, only one of the attacks was confirmed to have involved a suicide bomber, in Mosul, where police managed to shoot him before he could cause any fatalities, authorities said.
Awad Musa, 34, was on his way to work in Sadr City when the bus he was on became caught in a blast. Musa, wounded in his arm, was among the lucky.
‘‘Whenever we think it is over and we will live a stable life with no fear of explosion, we wake up again from this dream, to more disasters,’’ he said.
Authorities in Salahuddin Province, which seemed to be the worst-hit area, said they managed to defuse two car bombs and three roadside bombs without harm. ‘’If it wasn’t for our security plans, the loss would have been much bigger,’’ said Major General Jamal Tahir, head of police in Kirkuk.
He said authorities had killed the leader of the Al Qaeda cell there and, within hours of the attack, had arrested 12 insurgents, one of whom he said had committed suicide in his jail cell, hanging himself with his clothing.
The anger of Iraqis at their own government was on frequent display, especially in the southern province of Diwaniya, where a car bomb exploded in a busy vegetable market, killing five people and wounding 32.